Sulfuric acid, C16-C18 (even numbered) alkyl esters, sodium salts and C16-18 (even numbered) alcohols

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

As surfactants, the fatty alcohol sulfates tend to form micelles, potentially also solubilizing the fatty alcohols.
For such cases, the “Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance” (Version 6.0, July 2017, page 66ff) states:
“Consequently, the above definition for solubility of a single substance in water is not applicable to substances which are multi-component, such as multi-constituent or UVCB substances, i.e. complex substances. The usually accepted meaning of ‘solubility’ in such cases is ‘the composition of the aqueous solution formed at equilibrium under a defined set of conditions’. Temperature and the amount of substance added per unit volume of water (i.e. the ‘loading’) are the main factors to consider. It may not always be possible to establish that equilibrium of all components has been achieved; in these cases, time and type of agitation of the test vessels must also be described.”

GLP compliance:

no

Type of method:

flask method

Remarks:

slow stirr

Water solubility:

1.6 mg/L

Conc. based on:

other: C18 Fatty alcohol sulfate marker

Loading of aqueous phase:

100 mg/L

Incubation duration:

72 h

Temp.:

20 °C

pH:

6.3

Details on results:

OECD guidance 105 is designed for pure substances. The analysed substance is a multicomponent substance. Therefore, the method needed to be modified to consider the test item properties.
The test item consists of two different classes of compounds with different expected solubilities (fatty alcohols and fatty alcohol sulfates).
For such cases, the “Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance” (Version 6.0, July 2017, page 66ff) states:
“Consequently, the above definition for solubility of a single substance in water is not applicable to substances which are multi-component, such as multi-constituent or UVCB substances, i.e. complex substances. The usually accepted meaning of ‘solubility’ in such cases is ‘the composition of the aqueous solution formed at equilibrium under a defined set of conditions’. Temperature and the amount of substance added per unit volume of water (i.e. the ‘loading’) are the main factors to consider. It may not always be possible to establish that equilibrium of all components has been achieved; in these cases, time and type of agitation of the test vessels must also be described.”
The composition of the aqueous phase obtained for an experiment adapting the principles of the slow-stirring method as described in OECD 123 (Partition coefficient, slow-stirring method) is reported.
The formal concentration of the test item in the aqueous phase is:
1.6 mg/L by evaluation of the C18 Fatty alcohol sulfate marker via LC-MS
70 μg/L by evaluation of the C16 Fatty alcohol marker via GC-MS

A correction for the actual concentrations of the components in the test item was not carried out.
The pH values of the sample solutions was 6.3. The pH value of the de-ionised water used for the preparation of the test solutions was 6.3.

Conclusions:

water solubility: 1.6 mg/L

Key value for chemical safety assessment

Water solubility:

1.6 mg/L

at the temperature of:

20 °C